Challenges for Microbial and Thermochemical Transformation Toward Circular Bioeconomy

Abstract Successful establishment of a worldwide circular bioeconomy lies, at great extent, in establishing processes for the conversion of various industrial and municipal sidestreams, residuals, and wastes into feed, food, bio-based chemicals, and bioenergy. The diversity of materials, in terms of both amount and composition, around the world also calls for the development of a panoply of resource recovery strategies to meet country-level needs. This chapter provides an overview of biological (aerobic and anaerobic microbial methods) and thermochemical (combustion, gasification, and pyrolysis) processes with potential for the recovery of nutrients and/or their conversion into various products (e.g., electricity, heat, biofuels, biochemicals, and feed and food ingredients). The social aspects surrounding resource recovery and the limitations related to each of the described strategies are also addressed. Lastly, a discussion on integration and diversification of the considered strategies, leading potentially to faster implementation of circular processes, is provided.